The present invention is directed to a crankcase emission control system. The crankcase emission control system is useful in the crankcase breather of an internal combustion engine, such as a diesel engine.
Emission controls for internal combustion engines have become increasingly important as concerns over the environment have risen. One area where improvement has been noted is in crankcase emission controls.
Crankcase emissions result from gas escaping past the piston rings of an internal combustion engine and entering the crankcase due to high pressure in the cylinders during compression and combustion. As the blow-by gas passes through the crankcase and out the breather, the breather becomes contaminated with oil mist. The gas also contains wear particles and air/fuel emissions. In closed systems, the crankcase emissions are directed into the engine intake system causing internal engine contamination and loss of efficiency.
The oily crankcase emissions coat engine sites, such as the inside of engine compartments or chambers, fouling expensive components and increasing costs, such as clean-up, maintenance and repair costs. As the oily residue builds up on critical engine components, such as radiator cores, turbocharger blades, intercoolers and air filters, the residue becomes a xe2x80x9cmagnetxe2x80x9d for dust, grit and other airborne contaminants. The accumulation of contaminants on these components reduces efficiency, performance and reliability of the engine.
Crankcase emission control systems filter the crankcase particulate emissions and separate the oil mist from the crankcase fumes. The separated oil is collected for periodic disposal or returned to the crankcase.. Since most of the crankcase particulate emissions are soluble hydrocarbons, returning the cleaned, oil-free crankcase emissions to the engine inlet increases engine efficiency.
One particularly useful crankcase emission control system is shown in U.S. Pat. No. 5,564,401, owned by Diesel Research, Inc. In this system, a high efficiency filter and crankcase pressure regulator are combined into a single unit connected between the engine crankcase breather and the engine air intake. The filter separates small sized particles to prevent contamination of turbochargers, the aftercooler, and internal engine components. The pressure regulator maintains acceptable levels of crankcase pressure over a wide range of crankcase gas flow and inlet restrictions.
In the Diesel Research system, the pressure control assembly is located in a housing body and is configured to regulate pressure through the system as well as agglomerate particles suspended in the blow-by gasses. Inlet and outlet ports direct the blow-by gasses into and out of the housing body from the engine block. A filter housing enclosing a replaceable filter is removably attached to the housing body to separate any remaining oil from the blow-by gasses. The filter element can be easily removed from the filter housing for replacement, after removing the filter housing from the housing body. The oil drains down and collects in a reservoir at the bottom of the filter housing. An oil drain check valve is located in the bottom wall of the filter housing, and includes a free-floating (one-way) check valve. The check valve is connected through a separate return line to the oil pan or engine block to return the collected oil to the engine.
While the Diesel Research system has received acceptance in the marketplace as being a considerable improvement over previous systems, it is located external to the engine, and therefore requires additional space, plumbing, and must be mounted for easy access for replacement of the filter.
It is also known to install crankcase emission control systems internal to the cylinder head of the engine, such as shown in Aoki et al, U.S. Pat. No. 4,602,595. In the Aoki system, a pair of filter elements are supported vertically in the cylinder head. The first filter separates larger particles and oil droplets, while the second filter absorbs any fog-like fine particles which pass through the first filter. The oil separated by the first filter collects and drains down into an oil reservoir, where it passes through a check valve and is returned to the crankcase.
While the Aoki system conserves space, the cylinder head cover must be specially modified to support the filter elements. This adds machining cost. Further, there is no provision for draining the oil collected downstream of the second filter. It appears that any oil collected downstream of the second filter must drain back through the second filter and into the sump between the first and second filters, where it can then return to the engine through the check valve.
As such, it is believed there is a demand in the industry for a further improved crankcase emission control system for a crankcase breather, and more particularly for a compact filter assembly mounted within with the cylinder head of the engine; which does not require costly modification to the cylinder head cover; and which allows collected oil to easily return to the engine during operation and/or after shutdown.
The present invention provides a novel and unique crankcase emissions control system. The crankcase emission control system includes a filter assembly which is compact and fits within the cylinder head of the engine; does not require costly modification to the cylinder head cover; and allows collected oil to easily return to the engine.
According to the present invention, the filter assembly includes a housing adapted to be located within a cylinder head of an engine. The housing includes upper and lower casing members. A lower of the casing members includes one or more inlet ports which receive the crankcase emissions from the engine. An upper of the casing members is located flush against the inside surface of the cylinder head cover, and includes an outlet port. The outlet port of the upper casing member is received in the outlet port of the cylinder head cover and directs substantially oil-free gases back to the inlet of the engine for combustion. The housing can be fixed to the underside of the cylinder head cover with bolts.
The casing members support a pair of elongated filter elements. A first of the filter elements is a course filter, designed to remove larger oil particulate in the crankcase emissions. The other of the filter elements is a finer filter, designed to remove smaller oil particulates, and to coalesce oil in the emissions. The filter elements are located in adjacent, preferably surface-to-surface relation to one another with the first (coarser) filter element located upstream of the second (finer) filter element. A small sump channel is provided in the lower casing member under the elements to collect any oil agglomerating on the elements. A small drain opening is provided in the first sump to return oil to the engine.
A larger sump chamber is provided downstream of the second filter. The larger sump chamber collects oil coalescing on the downstream surface of the second filter. An outlet port is provided in the second sump, and a check valve is supported in the outlet port. The check valve has a simple, T-shaped structure and is designed to prevent unfiltered gases from being drawn into the second sump from the negative pressure in the filter housing when the engine is operating, but allows oil to easily drain back to the engine when the engine is idle or shut down. In the latter case, the collected oil forces the check valve downwardly into an open position to allow the oil to drain through the port back to the engine.
A plurality of fingers on the downstream side of the second filter element support the filter elements in the housing, and allow the filtered emissions to pass from the filter elements to the outlet port and back to the engine.
Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.